Dem bones...Dem old bones...

With 206 bones in the human body, you would think they'd get more fanfare. But many people take their bones - the entire skeletal system - for granted, pushing their bodies without attention to bone health.

The bones perform a number of essential functions. They support and protect the internal organs. Bones serve as levers and braces for muscles so the body can move freely. They also produce and store blood cells in the bone marrow. While many think of bones as hard parts of the body that change little, they are actually comprised of living tissue that's constantly growing and serving important functions.

When a baby is born, bones are made of flexible cartilage. As people age, the bones go through a process of ossification, where the cartilage is replaced by hard deposits of calcium phosphate and stretchy collagen. Calcium and sodium, in addition to other minerals, are also found in bones. Although bones are very strong, they are not indestructable. When a bone breaks, it is called a fracture.

According to the American Academy of Orthopedic Surgeons (AAOS), fractures are among the most common orthopedic complaints, with approximately seven million broken bones each year in the U.S.

Up until age 45, men are more likely to experience fractures. After age 45, the number of women experiencing fractures increases. Prior to age 75, the most common fracture occurs in the wrist. After age 75, hip fractures are the most common.

But fractures aren't the only problem that people face with bones, and understanding them can help in keeping bones healthy especially later in life.

Made mostly of collagen, bone is living, growing tissue. Collagen is a protein that provides a soft framework, and calcium phosphate is a mineral that adds strength and hardens the framework. This combination of collagen and calcium makes bone strong and flexible enough to withstand stress. More than 99 percent of the body's calcium is contained in the bones and teeth. The remaining one percent is found in the blood.

There are two types of bones found in the body; cortical and trabecular. Cortical bone is dense and compact. It forms the outer layer of the bone. Trabecular bone makes up the inner layer of the bone and has a spongy, honeycomb-like structure.

Throughout life, bone is constantly renewed through a two-part process called remodeling. This process consists of resorption and formation. During resorption, old bone tissue is broken down and removed by special cells called osteoclasts. During bone formation, new bone tissue is laid down to replace the old. This task is performed by special cells called osteoblasts. Osteoclast and osteoblast function is regulated by several hormones including calcitonin, parathyroid hormone, vitamin D, estrogen (in women) and testosterone (in men), among others.

People need to think of bone as a bank account where you "deposit" and "withdraw" bone tissue. During childhood and the teenage years, new bone is added to the skeleton faster than old bone is removed. As a result, bones become larger, heavier, and denser. For most people, bone formation continues at a faster pace than removal until bone mass peaks during the third decade of life.

Remember, in order to be able to make "deposits" of bone tissue and reach the greatest possible peak bone mass, the body needs to get enough calcium, vitamin D, and exercise, important factors in building bone.

After age 20, bone "withdrawals" can begin to exceed "deposits." For many people, this bone loss can be prevented by continuing to get calcium, vitamin D, and exercise and by avoiding tobacco and excessive alcohol use.

The most common disease

While there are many diseases in bones, one of the most common particularly in older people is Osteoporosis.

Osteoporosis develops when bone removal occurs too quickly or replacement occurs too slowly or both. People are more likely to develop osteoporosis if they did not reach their maximum peak bone mass during their bone building years.

Women are more likely than men to develop osteoporosis. This is because women generally have smaller, thinner bones, and because they can lose bone tissue rapidly in the first four to eight years after menopause due to the sharp decline in production of the hormone estrogen.

Produced by the ovaries, estrogen has been shown to have a protective effect on bone. Women usually go through menopause between ages 45 and 55. After menopause, bone loss in women greatly exceeds that in men. However, by age 65, women and men tend to lose bone tissue at the same rate. While men do not undergo the equivalent of menopause, production of the male hormone testosterone may decrease, and this can lead to increased bone loss and a greater risk of developing osteoporosis.

Osteoporosis is preventable for many people. Prevention is important because while there are treatments for osteoporosis, a cure has not yet been found. A comprehensive program that can help prevent osteoporosis includes the following.

â¢A balanced diet rich in calcium and vitamin D.

â¢Weight-bearing exercise.

â¢A healthy lifestyle with no smoking or excessive alcohol intake.

â¢Bone density testing and, when appropriate, medication.

Fractures

Fractures can occur from a number of causes. These include a blow to a bone, a fall, osteoporosis, a condition of weak or porous bones, or certain diseases or medications that affect bone density.

The best way to care for bone fractures is to prevent them in the first place. It is important to make safety a priority during work and play. Regular exercise is also a good supporter of good bones. Frequent and proper exercise improves bone health and strength.

People should also consume a varied diet and foods rich in calcium and vitamin D. Calcium and vitamin D are essential to maintaining healthy bones. Check with a doctor to see if a calcium supplement is necessary.